ALKATEL Desk Telephone ID Caller Repaired
I received this telephone in this condition that the LCD display of caller ID completely was dead.
The owner of telephone said by neglect telephone was fallen on the floor and after that LCD never turned on again.
Telephone itself was working good without ID caller. This problem could be of broken LCD or detaching of heat seal flat either one.
I opened the telephone and then I opened the LCD box, all accessories of LCD were installed inside this box. the heat seal paper flat of the LCD was not completely attached to LCD and partly was detached from LCD due to shock that telephone was received on the time of falling from the table to the floor, but when I push my finger on the paper flat and push that part to lcd body the digits were appeared on the screen.
This means that the LCD and the related IC are healthy.
(of course this is somehow also a common problem in humid part of the world that the humidity solves the glue and then evaporate by environment heat this cos the heat seal flat detach from LCD and the LCD will be no longer turn on any more.)
By above experiment I got this hope that by replacing the flat the LCD will return to life again. Then the job for replacing the bad flat paper starts:
- since there are many type of heat seal flat available in the market but in different size and numbers of graphite lines, first I count the graphite lines on the paper flat of mentioned, telephone, they were 12 line. I had in my stock such flat but with more graphite lines , by cutting I reached to my desired size
2- I removed the old paper flat from the LCD and pcb completely
3- I cleaned the surface of LCD, the place that old graphite lines were attached and sticked to the LCD, (by the help of thinner and Q-tips)
I also cleaned and made it shiny the pcb part that the other side of flat were attached on pcb this must be very clean to see the golden color of metal on the board
4-Most important part of this reinstallation of heat seal flat is: the graphite lines on the flat must be match to the lines on the LCD, one by one this needs some exercises as well as experience.
6- after I stick the flat to LCD same side that the old flat was sticked. by pressure of wrist and heat of special hammer head soldering iron (one must hold the head of the hammer head upon the flat for the few seconds till the flat stick to LCD)
Note 1: if you are working in the room with cooler and/ or cooling air condition you have to turn off it otherwise the heat of hammer head would not be enough.
5- after above steps same procedures are applied for pcb part of the flat .
6-after installation the new flat we must cover that portion of flat that is sticked to LCD and pcb with strong stick cloth ribbon to protect the flat against the heat and humidity of environment otherwise the life span of our job will be short
7- by connecting the telephone line to telephone showed that flat is correctly installed and lcd is on and digits appeared on the screen and The LCD of telephone returned to life again and telephone rescued
Cost of this repair was few cents.
NOTE 2: for installation of flat we need some exercises and after getting experienced many machines will need us for such services.
Note 3; the material of telephone flat was paper but I replace it with plastic film flat that is stronger.
This article was prepared for you by Mr Beh from Iran
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